Variable-speed driving mechanism.



PATIIIITBD AUG. 2o, 1907.

A II. A. GOQMBS.

VARIABLE SPEED DRIVING MEGHANISM.

'APPLICATION IAILED JSEPT. 17, 1904.

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HOWARD A. COOMBS, OF WASHINGTON, DISTRICT OF COLUMBIA. f*

VARIABLE-SPEED DRIVING TIECHANISM.

h.. Specication of Letters Patent. Application iled Septemberl?, 1904. Serial No. 224,824.

Patented Aug. 20, 1907.

To all whom it may concern:

Be it known'that I, HOWARD A. CooMns, a citizen of the United States, residing at Washington, District of Columbia, have invented new and useful vImprovements in Variable-Speed Driving Mechanism, of which the following` is a specification.

My invention relates to variable speed driving mechanism and its object is to so construct and arrange the mechanisml for driving machinery that the speed at which the latter will be driven will be automatically variedwhen variations in the load on such machinery fully explained hereinafter, infcpnne'ction with the dpetailed description of the drawirgsl nection withthe driving oimaehinetoolaand for convenience, I will describe itsapplicationtda lathe,`,al though it must be understoodthat its useulnessis in no wa)r limited thereto.l Let us asspme'by way of illustration, that a certain p horseA-pwerfwhen it is doing\ the maximum amount o fworkioi lwhiohfit is capable l' A without injury. This/amouiitoiQpQwer may be reany given instant by the cutting tool, in order that the 40 quired by a heavy cut when th`e lathe isrunning quite slowly, or it may. be requiredbya lighter cut when the lathe is running at a higher speed. From this ity ol- .lows as a natural consequence that thaspeed of the lathe should vary'inversely asV the resistance causdzt lathe may work at its highest efficiency, t'. e., produce the greatest output per day. Otherconsiderations,

I' such as wear anditear of the lathe, smoothnessA and accuracy of the cut, enter into the lproblem in practice, andtherefore subordinate speed-*changing means, such as cone-pulleys or the like may be employed, but the general proposition is, as stated above, thatJthe speed oi the lathe shouldalways increase whenh the cross- L sectional area of the chip being removed decreases and:

'vice versa.

i Itis customary to leave the control oi the speed at which the lathe is run to the judgment of the workman,

who only varies the same, either by shifting the-driving belt from one step of the cone pulley to another, or

. by shifting a gear or clutch, when thespeed becomes markedly too high or too low.- Naturally, he cannot taken, whereby a great saving l be continually'doing this, and in consequence the lathe A is run for most of the timebelow its maximum eiiciency.

By my invention I provide means whereby the speed is automatically governed by the load, so that without any attention at all on the part of the operator,v the lathe will speed up whenever the tool runs out of its cut or whenever the size of the cut decreases, and will slow down whenever the resistance increases. These variations in speed take place of course within certain limits, and the mechanism may be larranged in a manner tobe described, so that the power will be cut off entirely whenever an abnormal resistance is encoun tered, whereby a safe guard against` accident and breakage is provided. It will be noticed also as a natural consequence of the operation described, that the lathe will always runat full speed when no'cut isbeing of time is effected,` as on the return travel of the carriage. I In the accompanying drawing, Figure 1 is a side clefI vation, showing my invention applied to a speed-varyin g countershaft of the friction roller type; Fig. 2 is a detail bottom plan view of Fig. 1.and Fig. 3 is an' end view of the driving pulley. My invention is particularly designed for use i'n-con- In Fig. 1\, IY have shown my invention as applied to va speed-contrellinghunterswttgeweral' utilityandd applicatiomthe samebeing of'the typeshown in the patent to' Hoffman, Nojdlwteerring to said gures, 1 is a framecarryig the bearings 2, 3, 4, and 5, for the shaft 6, anda bracket 7 which carries the pivot 8 of lever 9. The shaft 6 is driven from pulley 10 "through sleeve 1l, disks l2 and `1B,.riction`rollers .14

and disks 15v andasn thesaid patent to Hoffman;

the angular position of the ollers' 14, of'which there l are a pair between each pair of disks, may be varied as ih Asaid patent to vary the speed of the driven memnected to the machine to be Er'ivenasfby-aibelt on pulley V3Q. In the aforesaid patent this-is' accomplish'ed by hand,` while I have 'providedgautomatic ber, i. e.,\the shaft 6, which, in practice, will be conl means for this purpose.M The rim'of the pulleyslO is' A.

lfree to rotat'erwithinclimits around its hub, which is a part of, or attached Yto sleeve 11,-saidnrimheing provided withr-aflradial inwardly projecting lug 17, and

said hub being p'mvidedavith a radial outwardl prpjecting lug 18,.betweei`1 which lugs are arranged springs 19 and 20. This construction may be varied considerably without departing fromrmytwention, the essen- -tial featurev being the yielding connectiorfbetween the hub'and rim of thepulljeyor gear.

Formed integral with the rim of'pulley 10 is a sleeve l having cam-surfaces 21, which coperate with like surfaces on a sleeve 22, which is-keyed to slide but not 4 rotate on sleeve 1l. Sleeve 22 is kept pressed up against said. cam surfaces 2l by a'spring 23, the strength of which can beadjusted by a collar 24, screw-threaded into bearing 3 or'adjustable relatively thereto by other well known means.

Sleeve 22 has an annular groove 25, in which engages the yoked upper end of lever 9. The lower end of' this lever engages a slot 26 in aslidable bar 27, provided at one end with rack-teeth 2S on its opposite sides. These rack-teeth engage segments 29 fast on the lower ends ot vertical shafts 30, carrying at their upper ends yokes 31 in which are journaled the rollers 14 between disks 12 and 15. v

The rollers 14 between disks 13 and16 arecarred by similar yokes 31, swiveled to the upper ends of ver tical shaftsA 30, carrying at their lower ends similar segments 29. These are engaged by rack-teeth 32 formed on thevopposite ends of a slidable bai 33, which is bent downwardly, asl shown at 34, and runs parallel to and beneath bar' 27. A pinion 35, suitably jour naled in brackets 36 formed on or projecting from frame 1,-eng`ages rack teeth 37 and 38 formed on the upper and lowc'rsides o bars 33 and 27 respectively, so that `when motion is imparted by lever 9 to bar 27 in one direction, bar 33 will be caused to move equally in the other direction, whereby the points of contact of the rollers 14 with the pairs of disks l2 and 13 and l5 and. 16 will be moved relatively to the axis oi sha-tt 6 correspondingly in the same direction. As shown in this figure, increase inthe load will increase thevspeed of shaft 6, which result is desirable in some instances, but

it will be obvious that by reversing pulley 10 and placn I ing it adjacent to disk l2instead of disk 13, the opposite result will be obtained.

40 represents in a general way the shipper mechanism, by which the disks 15 and 16 are pressed against or away from rollers 14; this feature not being iii-any way different from'that oi the aforesaid patent to Hoffman, does not need any detailed description.

In practice, manual means for reversing the lathe will be provided, either by reversing the motor or by the shitting of a 4clutch or a gear in the intermediate gearing; preferably also, manual means for controlling the speed, within limits, will be employed in addition to the automatic means.

Having thus described my invention and its mode of use, what I claim is:

1. In a power transmitting gearing, the combination of a shaft, a pair of driven disks on said shaft, a sleeve `and an -intermediate pair of driving disks thereon between and opposed to said rolls angularly, a yieldable driving member connected` to said pair of driving disks end connections from said `driving member to said adjusting means.

the disks of the iirst pair; friction-rolls be-A -tween the opposed disks of both pairs, means to adjust 2. A countershaft, a pair' of friction disks thereon, one

of saidV disks being fast on said shaft, a pair of rollers adjustably supported between said disks, a driving member for theA other of said disks comprising a hub rigid with said disk, 'a rim yieldably connected to said hub, a'sleevejv. V

mounted for longitudinal but not rotary movement relatively to said hub and disk,.a lever engaging said sleeve at one end, and a bar connected to the other end of said lever and to said rollers to vary their angular position between saidldisks. 'A

3. in a power-transmitting,l gearing, the combination of a driving friction disk and a driven friction disk, an angularly'adjustable friction roll between said disks, a yieldable drivingr member operatively connected to said driving friction disk ,and connections between said driving `member and said roll whereby the angular position of the latter 'varies in accordance with the load upon said driving member, E

v 4. ,In a power transmittlnggearing,l the combination of "two driving friction disks, two driven friction disks, an-

gularly `adjustable friction rolls between each pair of disks, and a yieldable driving member mounted between saidA pairs of disks and operatively connected to said rolls whereby the angular' positionsv of the latter are by the amount of load on said driving member.

5. In a device of the class described the combination with a shaft, two pairs of friction disks carried thereby and intermediate friction rolls, of means to vary the` angular' positions of said rolls, comprising two parallel rackbars 'slidably mounted, a pinion interposed between and meshing with both said rack-bars, a yieldable driving member and a lever mountedto be actuated by the yielding of said member under load and connected to one of said bars lwhereby an increase of load on the shaft will controlled cause a movementv ofsald bars in opposite directions and thereby vary the angular positions of said rolls to de' 

